295 
fxus61 kctp 220157 
afdctp 


Area forecast discussion 
National Weather Service State College PA 
857 PM EST Friday Nov 21 2008 


Synopsis... 
a deep upper level trough will dominate our weather through 
Saturday...keeping central Pennsylvania unseasonably cold with 
lake effect and orographically enhanced snow showers tonight and 
Saturday. High pressure will build over the region Saturday night 
and Sunday. The next storm is slated for the Monday-Tuesday time 
frame. Post storm northwesterly flow should re-generate lake 
effect for the rest of next week. 


&& 


Near term /until 7 am Saturday morning/... 
upper level shortwave...which produced traffic snarling snow 
squalls across the lower susq valley earlier this evening...has 
moved east of PA. In it/S wake...more typical lake effect regime 
setting up overnight as anomalously cold...well aligned northwest flow 
passes over the eastern lakes. Latest infrared imagery already showing 
evidence of intensifying le bands /cooling tops/ downwind of Lake 
Erie. Ll divergence fields in 00z model data indicate multiple le 
bands affecting the northwest mountains through tonight. Locally heavy accums still 
appear very likely...especially over the snowbelt of Warren 
Colorado. Maximum Omega in the dgz should yield high snow/water ratios on 
the order of 20/1. Thus...additional accums of around 6 inches 
overnight seem quite likely over parts of Warren/McKean counties. 


Will expand the Winter Weather Advisory southward into Clearfield 
County...as ll divergence and quantitative precipitation forecast fields both support several 
inches of additional accums there over the next 24 hours. 


See recently issued public information statement /pnsctp/ for snowfall 
amounts so far. 


&& 


Short term /7 am Saturday morning through Saturday night/... 
the northwest will still be under the influence of the good 290-300 lake 
fetch and a decent Huron connection into Sat afternoon. The longer 
band/S could reach into the local area...so plan on encountering 
some snow showers on Sat around unv. The winds will be rather 
gusty Sat afternoon...making it feel much colder than the 20s in the 
forecast. 


Lake eff shsn should taper off Saturday evening...as heights rise 
and the inversion level drops. But some flurries will linger into 
Sat night across the north. That will set up perhaps the coldest night 
over all the area so far this winter with the fresh snow and 
lightening winds. 


&& 


Long term /Sunday through Friday/... 
cold weather pattern to continue through the extended...with a 
possible yet gradual warming trend for the second half of 
Thanksgiving weekend. 


Temperatures will moderate a bit Sunday into Monday ahead of the next 
cold front...but will still remain below normal. Precipitation moves in 
from the west Monday...reaching eastern sections by afternoon. 
Atmosphere may be warm enough ahead of front to support rain mixed 
with snow for several hours. 


System stalls to the east as upper trough again deepens. North/northwest flow 
will bring lake effect clouds and snow showers to mainly the 
western counties Monday night into Wednesday. As cyclonic flow 
continues...low pressure will intensify somewhere near the coast. 
There still remains some uncertainty of just how this low will 
play out...but regardless unsettled weather will start the 
Thanksgiving weekend. Trough lifts to the NE late in the period 
with improvement in store for the weekend. 


&& 


Aviation /02z Saturday through Wednesday/... 
band of heavy snow that brought 9 to 11 inches of snow in 
isolated spots between unv and ipt is gone. 


However...as winds back a little...snow showers and squalls 
will become a problem for bfd and jst later this evening into 
Sat. MVFR and IFR conditions will prevail at these sites. 


For unv and aoo...mainly VFR...but MVFR at times...especially 
later this evening into early Saturday morning. 


Ipt and MDT should stay VFR. Bands of heavier snow showers 
moved through the Harrisburg area earlier this afternoon. 


High pressure builds in for Sunday...with mainly VFR conditions 
expected. 


Rain showers will move in later in the day for mondday...as 
low tracks west of c PA. Mainly VFR conditions early in the 
day. 


A coastal low is expected to form Monday night into Tuesday... 
thus some wrap around and lake effect snow showers expected 
later Monday night into middle week...as system cuts off. 
Thus looking at an extended period of mainly non-VFR 
conditions. 


Mean trough and ridge just a little too far east for the 
coastal having a direct impact on c PA. However...we will 
remain much colder than normal into late in the week. 


&& 


Ctp watches/warnings/advisories... 
lake effect snow warning until 6 PM EST Saturday for paz004- 
005. 
Winter Weather Advisory until 6 PM EST Saturday for paz006-010- 
011-017. 


&& 


$$ 
Synopsis...dangelo 
near term...Fitzgerald 
short term...dangelo/Fitzgerald 
long term...beachler/rxr 
aviation...dangelo/Martin